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Over the past decade, one-dimensional nanostructures, including nanowires(NW), nanorods, nanotubes and nanobelts, with various compositions and morphology have been fabricated by many approaches[1-5]. Among a large variety of semiconductors, metal oxides have attracted much research interest because of their unique electronic and optoelectronic properties[6-8]. In particular, zinc oxide(ZnO) has a direct and wide band gap of 3.37 eV, a large excition binding energy of 60 meV, and its ability to form a varity of nanostructured configurations[9], which is emerging as a promising candidate for designing nanostructures in the field of short wavelength optoelectronic devices[10-11]. Such as light-emitting diodes[12], sensors[13], solar cells[14] and field-effect transistors[15]. However, the questions of ZnO should be given out. In order to optimize the electrical and optical properties of ZnO, doping the ZnO nanostructures with various elements has been widely used[16]. Kim et al. reported the Al-doped ZnO nanostructures[17], which indicated the optical transparency tend to be degraded due to the enhanced scattering caused by the dopping. Yayapao et al. reported the Dy-doped ZnO nanostructures[18], which showed weak near-band-edge-emission in the UV region and a strong broad band deep-level-emission, and the intensity of green emission decreased with the percent of Dy. Shi et al. reported the Co-doped ZnO and the result showed a pronounced red shift of UV emission with the increases of Co doping concentration for ZnO nanorods[19]. Among these elements, Mg-doping in ZnO is preferred because it can modulate the band gap within a certain range from 3.37 to 7.7 eV as MgO has a larger band gap(7.7 eV) than that of ZnO. The ionic radius of Mg2+ (0.057 nm) is very close to Zn2+ (0.006 nm), therefore, the replacement of Zn by Mg does not give rise to significant changement in lattice constants[20-25]. At present, Mg doped ZnO nanostructures have been deposition(PLD)[26], sol-gel deposition[27], hydrothermal synthesis[28]and chemical vapor deposition(CVD) etc. Among these methods, CVD is one of the most important approaches for growing high quality nanostructures, which has several advantages mainly including high crystallinity, controlled size and dimensionality[29-30].
In this paper, MgZnO NWs have been successfully fabricated via CVD using the mixture of the zinc oxide powder and commerical graphite poweder and Mg powder as the precursor material without any catalysts. The advantages of this method include facile and catalyst-free growth of MgxZn1-xO NWs on SiO2/Si substrate and the subsequent transfer-free fabrication of electronic or optoelectronic devices.